U.S. patent number 3,994,615 [Application Number 05/586,191] was granted by the patent office on 1976-11-30 for multiple part cutting tool.
Invention is credited to Rajendra K. Narang.
United States Patent |
3,994,615 |
Narang |
November 30, 1976 |
**Please see images for:
( Certificate of Correction ) ** |
Multiple part cutting tool
Abstract
A cutting tool having one portion including a cutting head and
another portion including a stem, the portions being separately
produced from the same or different metals, or nonmetals, ceramics
and the like, and then connected together in coaxial relation by a
slip, press, or shrink fit of a polygonal shank of uniform cross
section throughout its length on either one of said portions into a
complementary polygonal socket in the other portion. Novel means
are provided for adjustment of the portions generally radially of
the cutting axis to offset differences in concentricity due to
manufacturing errors and to assure firm and precise coaxial
relation of the assembled portions.
Inventors: |
Narang; Rajendra K. (Macedonia,
OH) |
Family
ID: |
24344692 |
Appl.
No.: |
05/586,191 |
Filed: |
June 12, 1975 |
Current U.S.
Class: |
408/226; 408/233;
279/83 |
Current CPC
Class: |
B23B
31/005 (20130101); B23B 31/02 (20130101); B23B
31/026 (20130101); B23B 2231/0204 (20130101); B23B
2231/0228 (20130101); B23B 2231/0284 (20130101); B23B
2240/28 (20130101); B23B 2251/02 (20130101); Y10T
408/90993 (20150115); Y10T 408/907 (20150115); Y10T
279/17821 (20150115) |
Current International
Class: |
B23B
31/02 (20060101); B23B 31/00 (20060101); B23B
051/02 () |
Field of
Search: |
;408/226,233,713,81
;279/83,100,103 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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|
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1,098,149 |
|
Jul 1955 |
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FR |
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392,663 |
|
Mar 1924 |
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DD |
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384,720 |
|
Nov 1921 |
|
DD |
|
Primary Examiner: Simpson; Othell M.
Assistant Examiner: Briggs; W. R.
Attorney, Agent or Firm: Leonard; John Harrow
Claims
Having thus described my invention, I claim:
1. A cutting tool comprising:
a metal cutting head member of predetermined composition;
a metal stem member of predetermined composition;
an axial smooth wall shank of polygonal cross section of uniform
size and shape on one end of one of said members;
the other one of said members having an axial, smooth wall socket
of like unform polygonal cross section and opening through one end
of said other one of said members;
said shank being received with radial clearance in said socket
through said open end and being mounted fixedly therein and holding
the members in approximate coaxial relation to each other;
adjustable securing means carried by said other one of the members
and have portions extending into the socket thereof and engaging
the shank for shifting the position of the shank in directions
transversely of the socket to place the members in coaxial
relation;
said adjustable securing means comprise at least two screws mounted
in said other member with their axes substantially coplanar and for
movement endwise inwardly into and outwardly away from the axis of
the socket; and
said screws being angularly disposed relative to each other about
the axis of the socket.
2. A cutting tool according to claim 1 wherein said screws are
positioned to engage the shank at circumferentially spaced apexes
thereof, respectively.
3. A cutting tool according to claim 1 wherein the screws engage
faces of the shank, respectively, at the transverse midportions
thereof.
4. A cutting tool according to claim 1 wherein said one of said
members also has a smooth wall socket of like uniform polygonal
cross section and opening through one end;
said shank is a separate element received in both of said sockets,
with those ends of the members through which the sockets open being
in face to face contact with each other; and
said adjustable securing means further include at least two screws
mounted in said one member with their axes substantially coplanar
and for movement endwise inwardly into, and outwardly out of, the
socket of said one member.
5. A cutting tool comprising:
a metal cutting head member of predermined composition;
a metal stem member of predetermined composition;
an axial smooth wall shank of polygonal cross section of uniform
size and shape on one end of one of said members;
the other one of said members having an axial, smooth wall socket
of like uniform polygonal cross section and opening through one end
of said other one of said members;
said shank being received in said socket through said open end and
being mounted fixedly therein and holding the members in coaxial
relation to each other;
characterized in that
the stem member is smaller is diameter than the head member
throughout its length;
a collar member of larger diameter than the stem member is slidably
fitted on the stem member at the end portion thereof adjacent the
head member;
the end of at least one of the collar and head members has a
plurality of radial grooves therein;
said grooves are elongated endwise, extend endwise generally
radially of he head and collar members, and are open laterally
toward the end of the other of the last mentioned members;
adjusting pins are disposed in the grooves, respectively, the
circumferential wall of each pin having a portion extending beyond
the end surface on the one of said last mentioned members toward,
and engaging, the adjacent end surface of the other of said last
mentioned members;
said pins being selected as to diameter, so as to adjust the stem
member and head member into assembled coaxial relation; and
means to secure the head member and stem member in the relative
position into which they have been adjusted by said pins.
6. A cutting tool comprising:
a metal cutting head member of predetermined composition;
a metal stem member of predetermined composition;
an axial smooth wall shank of polygonal cross section of uniform
size and shape on one end of one of said members;
the other one of said members having an axial, smooth wall socket
of like uniform polygonal cross section and opening through one end
of said other one of said members;
said shank being received in said socket through said open end and
being mounted fixedly therein and holding the members in coaxial
relation to each other;
characterized in that said other one of the members has a pluraltiy
of grooves therein opening laterally into the socket through walls
of the socket, respectively;
said grooves are elongated and, endwise, extend generally
longitudinally of the socket;
adjusting pins are disposed in the grooves, respectively; and
said pins are selected, as to diameter, so that the said
circumferential wall of each pin extends into the socket the proper
distance to firmly engage the shank when the shank is in coaxial
relation with the axis of the cutting head member.
7. A cutting tool according to claim 6, wherein said pins are
elongated, hardened, and ground cylindrical rollers.
8. A cutting tool according to claim 6, wherein each pin comprises
a row of hardened and ground balls.
Description
BACKGROUND OF THE INVENTION
1. Field of Invention
Rotary cutting tools.
2. Description of the Prior Art
Generally, in the manufacture of cutting tools, such as drills,
reamers, thread milling cutters, hobbing tools, and the like, the
tool stem and cutting head are made integral with each other, the
stem being of the same high speed steel or alloy s the head. This
one-piece structure is finish ground to the shape and configuration
desired. Any manufacturing defect in either the stem or head
renders the tool useless for its intended purpose. Sometimes it can
be reprocessed to eliminate the defect, but only at a substantial
cost.
One attempt to overcome this disadvantage is to form the stem and
cutting head separately and of different metal, and then to join
them together. Generally, in this practice, the stem is made of a
cheaper steel, such as ordinary carbon steel, and the head of high
speed cutting steel or alloy. To this end the cutting head is
formed with an axial cylindrical shank which is received in a
complementary socket in the separately made stems, though in some
instances the socket is formed in the cutting head and the shank is
provided on the stem.
However, in quantity production of such tools, difficulties arise
in forming the stem and the head separately with such high
precision consistently that they will have true concentricity and
coaxial relation when assembled. To overcome this difficulty, the
head and stem are often assembled prior to any grinding of the tool
head or the tool stem. The configuration of some of these shanks
and sockets are such that the metal of the head or stem is placed
under undue stress during and after assembly. As a result, upon
heating and cooling of the tool in use, and subjection of the tool
to torsional stresses, fractures and deviations from concentricity
often occur in the multi-piece structure. Further, if the cutting
head or stem is damaged the damaged part cannot be removed and a
like new part substituted therefor.
In accordance with the present invention, the tool is formed in two
separate parts; for example, the stem and head of the tool are
formed separately, and of different metal, with interfitting
polygonal connecting parts, and then are assembled and precision
finish ground to final proportions and configuration with assurance
of concentricity of true coaxial relation of the head and stem. If
either the stem or head is damaged or worn out, the two can be
disassembled without damaged to, or marring of, the undamaged or
unworn one of the two and the worn or damaged one replaced with a
new one at the work site, at a considerable saving in time and
cost, thereby resulting in an increase in productivity of the
machine in which the cutting tool is used.
The separate parts can be heat treated independently of each other,
so that both can be given the heat treatment most nearly optimum
for imparting the necessary characteristics for their particular
functions in the combination. The separate treatment can be carried
on in different furnaces concurrently, dependent upon the type of
metal, with assurance of a ore uniform product. Since each part of
the tool is smaller than the whole and is of different metal, the
heat treating cycle for each part can be simplified. Further, the
machining cost of keeping each part straight and the cost of the
necessary fixture for holding each part while machining are
reduced.
Again, the life of the grinding wheels and the like used for
grinding during original production is greatly increased. Scrap and
reworking are less costly. If only one part of the tool is worn out
or damaged, the other part can be salvaged readily, whereas
salvaging of an entire one-piece tool normally necessitates the
step of hard chrome plating and regrinding of the entire tool, and
such plate and regrinding are expensive, both as to time and labor,
and also as to the chrome metal required. With the present tool,
only one part needs to be plated if a like salvage operation is to
be used.
In accordance with the present invention, specific means are
provided for adjusting the concentricity of the separate stem and
head of the tool, so as to overcome deviations, if any, from
precision in original manufacturing steps prior to grinding, and in
replacement of one or the other parts of the tool,
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is shown in the accompanying drawings as
applied to a simple drill, its use in other rotary tools being
readily apparent from the illustrative example.
FIG. 1 is a side elevation of a drill embodying the principles of
the present invention;
FIG. 2 is an exploded side elevation of the drill illustrated in
FIG. 1, showing the parts in position for assembling;
FIG. 3 is an enlarged fragmentary view of the drill illustrated in
FIG. 1, showing one means for adjusting the parts for
concentricity;
FIG. 4 is a cross sectional view of th drill, similar to FIG. 3,
and is taken on the line 4--4 in FIG. 3;
FIG. 4A is a cross sectional view, similar to FIG. 3, illustrating
a modified form of the concentricity adjusting means for the drill
parts;
FIG. 5 is an enlarged fragmentary longitudinal sectional view of a
drill, such as illustrated in FIG. 1, and illustrating the use of
modified means for centering the drill parts, and is taken on line
5--5 of FIG. 6;
FIG. 6 is a cross sectional view of the drill illustrated in FIG. 5
and is taken on line 6--6 thereof;
FIG. 7 is a cross sectional view of the part of the drill which
includes the cutting head of FIGS. 5 and 6, with the shank removed,
and illustrating the grooves used in centering the parts which
include the head and stem, respectively;
FIG. 8 is a view similar to FIG. 7 and showing a modified form of
the grooves;
FIG. 9 is a fragmentary longitudinal sectional view, similar to
FIG. 5, illustrating another modified form of centering pin;
FIG. 10 is a diagram illustrating a difficuty in centering a head
and stem of a tool by the conventional shimming method;
FIG. 11 is a modified form of the invention, showing a further
connecting means between the part of the drill including the
cutting head and the part including the stem; FIG. 12 is a
fragmentary longitudinal view, partly in section, illustrating the
application of the invention to large diameter drills;
FIG. 13 is a cross sectional view taken on line 13--13 of FIG. 12;
and
FIG. 14 is a view similar to FIG. 1 showing a different specific
structure embodying the invention and in which the fluting is
carried beyond the juncture of the head onto the adjacent part of
the stem.
Referring to FIGS. 1 through 3 of the drawings, the drill,
indicated generally at 1, includes a stem 2 which is cylindrical or
tapered, as is conventional. The stem has an axial socket 3 opening
through one end. The socket 3 is of polygonal cross section,
preferably square, pentagonal, or hexgonal, and is of substantially
uniform cross section throughout its length. The stem 2 preferably
is made of plain, medium or high carbon steel, depending upon the
uses to which the drill is to be put.
For connecting the stem 2 to a tool head, a short rod 4 of cold
drawn, plain, medium or high carbon steel, with a cross section of
uniform size and shape throughout its length, and of the same shape
as that of the socket 3, but very slightly larger in its cross
dimensions, is press fitted or shrink fitted permanently in the
socket 3 and extends beyond one end of the stem 2. Near its outer
end, the rod 4 has notches 5 at its corners, for purposes later to
be described. Generally, these notches are V-shaped. The stock for
the rod 4 can be purchased in the cross section desired and readily
cut to length and ground or machined for slip, press, or shrink
fitting into the socket 3. The complementary wall surfaces of the
rod and those of the socket are smooth and planar, and free from
knurling and the like.
The flutted cutting portion or head 6 of the drill 1 is made of
high speed or tool steel or other alloy, depending upon the use for
which it is designed. The heat 6 is provided at the end opposite
its cutting tip with a socket 7 which, throughout its effective
length, preferably is of substantially the same cross sectional
shape as the rod 4, but the same or very slightly smaller in cross
sectional dimensions. The walls of the socket 7 are smooth and
planar. The rod 4 fits the socket very precisely with a slide,
press, or shrink fit. As a result, the head 6 can be removed from
the rod 4 and a new or duplicate head 6 substituted. In the case of
a slide fit, this can be done with the tool head and stem in their
original condition. If press or shrink fitted, they are subjected
to localized heating of the joined portions of the head and rod for
a very short time, keeping heat at low intensity and then
withdrawing the heat from the rod.
The heat 6 is provided with at least two, and preferably three or
four, threaded radial bores 8 which are angularly disposed relative
to each other about the socket axis to such a degree screws 9 can
be manipulated therein to engage and move the head 6 and rod 4 into
concentric relation and secure them in that position in case of
slight manufacturing errors. For example, with a square rod 4, two
screws 8 arranged 90.degree. from each other at two adjacent
corners of the socket 7 can be used. The screws 9 are tapered at
their inner ends so as to enter the notches 5. With this
arrangement, two components of movement for centering are provided.
If the rod and head cannot be centered in one relatively rotated
position about the tool axis, they can be separated and rotated
90.degree. or 180.degree. relative to each other, reconnected and
centered by the screws 9.
On the other hand, if three or four screws are provided, centering
can be effected without separating and rotating the parts. The
screws 9 are particularly desirable when a slip fit between the rod
4 and head 6 is provided, as they lend themselves readily to
centering of the rod 4 and head 6, and also to prevent axial
separation during retraction of the tool from the work.
Instead of the screws 9 engaging the corners of the rod 4, screws
9a may be used and mounted in bores 8a positioned so that the
screws 9a engage the faces of the rod 4a, as indicated in FIG.
4A.
Since the rod 4 has a slip, press, or shrink fit engagement with
the head 6, the head 6 can readily be removed from the rod 4 for
replacement without applying any gripping jaws to the stem 2 and
without marring either the head or stem, by applying a rapid low
heat to the surface of the head 6 at the location of the socket, so
as to enlarge the socket to a substantial degree to facilitate
withdrawal of the rod 4 from the head.
As an alternative, the rod 4 can be formed as an integral part of
the stem 2. This alternative is expensive due to the higher quality
steel that might be required for the stem 2 as compared to the rod
4, and the machining procedures required to form the rod 4 as an
integral part of the stem.
As an additional alternative, instead of adjustment between the rod
4 and head 6, radial threaded bores 10 may be provided in the stem
2 and screws 11 mounted therein for adjusting the rod 4 radially in
the stem, in the same manner as the head 6 and rod 4.
In some instances, the rod 4 may not be quite square, but slightly
trapezoidal in cross section, one side sloping slightly inwardly
transversely of the cross section of the rod and socket, leaving a
space x, as illustrated diagrammatically in FIG. 10. The ordinary
flat metal shims could not be used practically for centering under
such conditions, because the space x between the rod 4 and the
adjacnet wall of the socket 7 might be large enough to receive the
shim at one edge of the face, but not at the other edge. With a
space x of tapering cross section, a shim of constant thickness
could not be inserted, and it would be impractical to provide shims
with all different degrees of tapered cross sections for meeting
the manifold conditions that might arise. The present arrangement
can overcome this defect in manufacture as no shims of this
character are required.
Instead, in the modified form of the invention illustrated in FIGS.
5 through 7, the drill has a stem 12, such as hereinbefore
described, with an axially projecting rod 14 having an axial socket
15. One or more screws 16 may be mounted in the head 14 and
cooperate with the rod 12 to retract the head when the tool is
retracted from a bore in a workpiece.
Each groove 17 may be a half-cylinder which is intersected at its
diameter by the associated socket wall so that the circumferential
walls of different sizes of pins 19 may be inserted therein, up to
the full radius of the socket, endwise through the open ends of the
grooves 17 with a slip fit and can protrude radially beyond the
socket wall into the socket the required distance, depending on the
diameter of the pin, and thus bear against the adjacent face of the
rod 13.
If desired, instead of the grooves 17 being half-cylindrical, they
may be less than half-cylindrical, with their centers spaced
inwardly of the socket 15 from the socket walls.
Again, as illustrated in FIG. 8, the centering grooves 17a may be
in the form of a mere V-shaped cross section, disposed with their
side walls flaring away from each other in a direction toward the
axis of the bore 15a.
The grooves described permit a wide range of adjustment, as the
pins used can be selected in diameter so that the circumferential
wall of each may extend into the bore 15 or 15a from less than a
thousandth of an inch to several thousandths of an inch.
It is to be noted that each of the grooves 17 is midway between the
edges of the associated face of the rod 13.
The head 14 and rod 13 are thus brought into coaxial relation,
after measurement of the eccentricity and selection of a proper
pin, or by trial and error with selected ones of the pins 19. The
screw or screws 16 are then tightened to secure the rod 13 and head
14 from separation axially.
Instead of cylindrical pins 19, such as hardened and polished
rollers of the type used in roller bearings, balls 20 of the type
used in ball bearings may be used for pins. In such case, each
groove contains a row of balls of equal diameters, as illustrated
in FIG. 9. Since the pins 19 or balls 20 are of uniform diameter,
the effect in either case is a linear contact with the transverse
center of each face of the rod at the transverse center of each
face of the socket. Therefore it does not matter whether the rod is
truly square or trapezoidal, or precisely of the polygonal shape
desired, as an out-of-round rod, regardless of cross sectional
shape can be brought to concentricity by the centering means
disclosed.
In FIG. 11, another modification is illustrated in which a stem 21
and head 22, each provided with an axial polygonal socket, are
joined by a rod 23 in the manner heretofore described in connection
with FIGS. 1 and 2, except that, instead of radial screws as
therein described, a single transverse bore 24 extends entirely
through the head 22 and rod 23 and a pin 25 is inserted
therein.
In FIG. 12, a large size drill is illustrated in which a large
diameter head 27 is made separate from a smaller diameter stem 28
having an integral shank 28a. An enlarged collar 28b is slipfitted
on the stem. The collar 28b is connected to the head by bolts 29.
Such a stem may be entered as heretofore described in FIGS. 1 and 2
or by pins 30, as in FIGS. 5 and 6, and, if the axes of the head
and stem are oblique to each other, such obliquity can be
eliminated by providing radial grooves 31 in the color 28b, and
adjusting pins 32 therein which function to rock the stem into
coaxial relation with the head in the manner that the pins 19
function for their centering adjustment.
In FIGS. 1 and 2, the drill is shown as having an unfluted stem,
the juncture between the head and stem being positioned beyond the
ends of the fluting on the head in a direction away from the
cutting tip. In many instances, it is desirable that the fluting,
especially on very long drills, extend beyond this juncture and
into the stem. Such a modification is illustrated in FIG. 14
wherein a drill 33 similar to that in FIG. 1 is illustrated, but
differing in that it has a stem 34 and a head 35 in which the
flutes 36 continue from the tip of th head, across the juncture of
the head, and onto the stem. The two parts, the head and stem, are
connected by a rod 37 in the same manner as the like parts in FIG.
1 are connected by the rod 4.
* * * * *